Device for spraying a predetermined dose of a fluid, and a method of filling the device

ABSTRACT

A device for spraying a single dose of a fluid in divided form includes a cylindrical tank (1) containing the dose of fluid, a piston (2) sliding in the cylindrical tank (1), a pusher for the piston (2), and outlet passage (5, 6) capable of communicating with the cylindrical tank (1). The piston (2) is displaceable relative to the pusher between a storage position, in which it prevents communication between the outlet passage (5, 6) and the cylindrical tank (1), and an actuation position, in which it puts the outlet passage (5, 6) into communication with the cylindrical tank (1). According to one aspect of the invention, the piston (2) is maintained in its storage position by wedging.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for spraying a predetermined dose of afluid, and to a method of filling the device. More particularly, theinvention relates to a device containing a single dose of fluid andsuitable for discarding after said dose has been dispensed. The fluid tobe sprayed may be a medicine, a cosmetic, or the like. The device of theinvention is more particularly intended for spraying into the nose, butit could be used for other purposes: spraying into the ear, under thetongue, etc.

2. Discussion of the Related Art

The single dose may optionally be subdivided into a plurality ofsubdoses, as disclosed in Document EP-A-0 311 863.

Such devices are known in the state of the art. For example, documentEP-A-0 311 863 describes a device comprising a cylindrical tank of fluidin which there slides a piston which is secured to an actuator pusher.The device also includes an outlet passage in communication with thetank of fluid. However that outlet passage is not airtight so the fluidcontained in the tank may oxidize or become polluted in contact with theair during storage.

SUMMARY OF THE INVENTION

A particular object of the present invention is to avoid that drawback,but without significantly increasing the cost of the device which issuitable for discarding after being actuated a single time.

The present invention therefore provides a device for spraying a singledose of a fluid in divided form, the device. comprising at least:

a cylindrical tank containing said dose of fluid;

a piston slidable in said cylindrical tank;

actuator means for actuating the piston; and

an outlet passage capable of communicating with said cylindrical tank,said piston being displaceable relative to said actuator means between astorage position in which it prevents communication between said outletpassage and said cylindrical tank, and an actuation position in which itputs said outlet passage into communication with the cylindrical tankthe piston being placed so that a pressure obtaining in the cylindricaltank attracts the piston towards its actuation position,

characterized in that tho piston is held in its storage position bywedging, and can be displaced towards its actuation position only if thepressure that obtains inside the cylindrical tank is sufficient forunwedging it.

In a particular embodiment of the invention, the actuator means comprisea cylindrical portion that extends between an end close to thecylindrical tank and an abutment that is further from the cylindricaltank, said end close to the fluid tank is secured to a ring, said fluidoutlet passage is disposed at least in part inside said cylindricalportion of the actuator means, said fluid outlet passage opens out fromsaid cylindrical portion between said ring and said abutment in thevicinity of said ring, the piston includes an internal sleeve thatslides over said cylindrical portion of the actuator means, and saidpiston is in sealing contact with said ring while in the storageposition.

Advantageously, the piston includes an outside peripheral sealing lipwhich slides in sealed manner inside the cylindrical tank and which iswedged between said tank and the ring when the piston is in its storageposition. In a particular embodiment, the ring includes an annular ribextending towards the piston, the piston includes an annular grooveadapted to receive the rib of the ring, the piston includes an annularrib directed towards the ring and inside said annular groove, and thering includes an annular groove adapted to receive the annular rib ofthe piston. In which case, the ring may include at least one passageputting the tank into communication with the groove of the piston whensaid piston is in its storage position, and the rib of the piston is insealing contact with the groove of the ring.

Advantageously, the cylindrical tank includes an end wall, and the ringincludes a face facing towards said end wall and substantiallycomplementary in shape to said end wall, and said face of the ring comesinto abutment against said end wall at the end of the stroke of thepiston, such that substantially all of the fluid contained in the tankis expelled.

The piston may optionally be urged towards its storage position byresilient means.

The internal sleeve of the piston may be pressed against the abutment ofthe actuator means when the piston is in its storage position, and thedisplacement of the piston towards its actuation position takes place bydeformation of at least a portion of the internal sleeve.Advantageously, the internal sleeve of the piston then includeslongitudinal slits over a fraction of its length in the vicinity of saidabutment of the actuator means so as to facilitate deformation of saidinternal sleeve.

The sleeve may be pressed in sealed contact against said abutment of theactuator means when the piston is in its actuation position.Advantageously, said abutment includes a concave annular surfacesurrounding the cylindrical wall with its concave side facing towardsthe sleeve, and said concave annular surface deforms radially towardsthe inside of a free end of said sleeve when the piston is in itsactuation position. In a variant, the sleeve of the piston may slide insealed manner over the cylindrical wall of the actuator means.

In a particular embodiment, the piston includes a cylindrical portionwhich slides over a complementary cylindrical portion of the ring whilecontinuing to interrupt communication between the cylindrical tank andthe fluid outlet passage so long as the piston has not moved away fromthe ring by a predetermined distance.

In another particular embodiment of the invention, the cylindrical fluidtank includes a filler orifice suitable for receiving a plugging bead,and said orifice is extended towards the outside of the tank by a ductprovided with longitudinal slits, said bead being capable of beingreceived as a force-fit inside said duct in an intermediate positionwhere it allows the tank to communicate with the outside via saidlongitudinal slits.

The present invention also provides a method of filling theabove-specified device, the method comprising at least the followingsteps:

the device is placed in a vacuum chamber and is kept under a vacuum;

a predetermined volume of fluid is inserted in the cylindrical tank; and

the cylinder tank is closed under a vacuum;

characterized in that said predetermined volume of fluid is measured bymeasurement means external to the device of the invention and may haveany value that is not greater than the total volume of said cylindricaltank.

The device may include resilient means urging the piston towards itsclosure position.

In an advantageous embodiment, at rest said piston is in sealing contactwith said ring around a peripheral line close to the cylindrical wall ofthe tank so that only a radially outer portion of the piston isinitially exposed to the pressure that obtains inside the tank, suchthat the section of the piston which is exposed to the pressure thatobtains inside the tank increases suddenly when the piston separatesfrom the ring, thereby encouraging clean opening of communicationbetween the tank and the outlet passage.

In another embodiment which is applicable to any device of the generaltype specified in the introduction, it includes locking means thatprevent the pusher from moving axially relative to the tank.Advantageously, said locking means are unlockable by rotating the pusherrelative to the tank. Advantageously, the locking means remain blockedin the unlocked position after they have been unlocked. The lockingmeans may be constituted by at least one breakable bridge of materialbetween the pusher and the tank.

In an embodiment that may be applied to any device of the general typespecified in the introduction, means for preventing involuntaryactuation thereof. Advantageously, it includes at least one zone ofbreakable material that forms an abutment opposing actuation and that isbroken during actuation.

In an embodiment that may be applied to any device of the general typespecified in the introduction it includes means for preventing the tankfrom being separated from the pusher. Advantageously, said means includesnap-fastening means that are in the snap-fastened position at leastwhile the device is in its rest position. Advantageously, saidsnap-fastening means are also in the snap-fastened position when thedevice in its end-of-actuation position.

The present invention also provides a method of filling theabove-mentioned device, the method comprising at least the followingsteps:

the device is placed in a vacuum chamber;

a predetermined volume of fluid is inserted in the cylindrical tank;

the vacuum chamber is evacuated; and

the cylindrical tank is closed under vacuum; characterized in that saidpredetermined volume of fluid is measured by measurement means externalto the device of the invention and may be of any value that is notgreater than the total volume of said cylindrical tank.

BRIEF DESCRIPTION OF THE DRAWING

Other characteristics and advantages of the invention appear from thefollowing detailed description of various embodiments of the inventiongiven as non-limiting examples, and with reference to the accompanyingdrawings.

In the drawings:

FIG. 1 is a longitudinal section view through an embodiment of thedevice of the invention, in its storage position;

FIG. 2 is a perspective view of the FIG. 1 device;

FIG. 3 is a detail view of a portion of the FIG. 1 device;

FIG. 3A is a view of the underside of the ring 10 in FIG. 3, as seenlooking along A in FIG. 3;

FIG. 3B is a view similar to FIG. 3, showing a variant of the device ofthe invention;

FIG. 4 is a fragmentary longitudinal section view through the device ofFIG. 1 in its end-of-actuation position; while FIG. 4A is an expandedview of select portions of FIG. 4.

FIG. 5 is a fragmentary view in longitudinal section through a variantdevice of the invention in its storage position;

FIG. 6 is a fragmentary longitudinal section view through anothervariant of the device of the invention in its storage position;

FIG. 7 is a fragmentary longitudinal section view through the FIG. 6devices in its end-of-actuation position;

FIG. 8 is a section view similar to FIG. 3 for a variant of theinvention that is particularly adapted to the configurations of FIGS. 6and 7;

FIG. 9 is a fragmentary longitudinal section view through anothervariant of the device of the invention in its end-of-actuation position;

FIG. 10 is a detail view of the FIG. 9 device;

FIG. 11 is a section view through another variant of the device of theinvention;

FIG. 12 is a diagrammatic longitudinal section view through a variant ofthe device of the invention, in its end-of-actuation position, the rod 4and the piston 2 being omitted;

FIG. 13 is a side view in longitudinal section through the FIG. 12device in its storage position;

FIG. 14 is a section view on line A--A of the FIG. 13 device;

FIG. 15 is a side view of another variant of the device of theinvention;

FIG. 16 is a fragmentary, section view through another variant of thedevice of the invention; and

FIG. 17 is a section view through another variant of the device of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 4 show a first embodiment of the device of the invention.This device is designed to spray a single dose of a fluid, generally ofthe order of a few milliliters. The device of the invention is thussmall in size, and measures a few centimeters in its greatest dimension.It is generally made of a plastics material.

As shown in FIG. 2, the device of the invention includes a pusher 3provided with an outlet endpiece 18 having an enlarged base 19 fromwhich there extends radially outwardly a thrust surface 20 that is inturn extended by a skirt 21. A pump body 22 is mounted inside the skirt21 and includes thrust wings 23 adapted to slide inside said skirt 21.The device may be actuated by being held between the thumb and one ortwo fingers, the thumb being pressed against the thrust wings 23 and theother fingers being pressed against the thrust surface 20. To facilitateactuation, the skirt 21 generally includes a recess 24 for receiving thethumb.

With reference to FIG. 1, the pump body 22 includes a cylindrical tank 1which extends between an open end 25 and an end wall 16 provided with afiller orifice 26. The filler orifice 26 may be dosed by a bead 27 thatconstitutes a force-fit inside said orifice, or by any other plug means.Advantageously, the skirt 21 of the pusher 3 has an inwardly-directedsnap-fastening lip 28 on its free end that serves to keep said thrustwings 23 inside said skirt 21.

The enlarged base 19 of the outlet endpiece 18 is constituted by acylindrical wall 29 disposed around the cylindrical tank 1 and whichextends between the thrust surface 20 and annular wall 9 which itselfextends radially inwards to the outlet endpiece 18. The outlet endpiece18 extends between said annular wall 9 and an outlet end 30 including anoutlet orifice 6. The outlet endpiece 18 is hollow and it projects acertain distance inside the cylindrical wall 29 of the enlarged base 19in the form of a cylindrical wall 7 that extends to an end 8. Thus, theoutlet endpiece 18 and the cylindrical wall 7 delimit a cylindricallongitudinal channel 31 in communication with the outlet orifice 6.

A rod 4 that is also cylindrical is a force-fit inside the longitudinalchannel 31. The rod 4 extends from a first end 32 placed in contact withthe outlet end 30 of the outlet endpiece 18 to beyond the end 8 of thecylindrical wall 7, at which point said rod 4 extends radially outwardsin the form of a ring 10. The rod 4 includes one or more outside grooves5 extending along its entire height and in communication with the outletorifice 6, generally via grooves formed in the first end 32 of the rod 4in well-known manner.

The device of the invention also includes a piston 2 that slides in thecylindrical tank 1 and that is capable of sliding over the cylindricalwall 7 of the pusher between the ring 10 and the abutment-formingannular wall 9. In the example shown in FIG. 1, the piston 2 includes aninternal sleeve 11 that extends to a free end 43 close to the annularwall 9 of the pusher and that slides over the cylindrical wall 7. Inaddition, the piston 2 includes an outer skirt 33 that slides in sealedmanner inside the cylindrical tank 1.

FIG. 3 is a detail view showing the structure of the piston 2 and of thering 10. The ring 10 includes an annular rib 12 facing towards thepiston, and the piston 2 includes an annular groove 13 facing towardsthe annular rib 12. The annular groove 13 of the piston is inwardlydelimited by a rib 14 and outwardly by a peripheral outer sealing lip 34of the skirt 33 which slides in sealed contact inside the cylindricaltank. The ring 10 also includes a groove 15 adapted to receive said rib14. When the piston 2 is in a storage position, as shown in FIG. 3, theannular rib 12 of the ring 10 is a force-fit in the annular groove 13 ofthe piston, and is wedged between the sealing lip 4 and the rib 14 ofthe piston. During assembly of the device, the piston 2 is initiallyassembled on the ring 10 by engaging the annular rib 12 in the groove13. Then the rod 4 is forced into the longitudinal channel 31 of thepusher and the piston 2 is inserted into the cylindrical tank 1. Tofacilitate such insertion, the cylindrical tank 1 advantageouslyincludes an inside chamfer 41 at its open end. When the sealing lip 34is inset-ted in the chamfer 41, it is progressively deformed radiallyinwards so as to clamp against the rib 12 which is thus compressedbetween the rib 14 and the lip 34.

In the particular example shown in FIGS. 3 and 3A, contact between thelip 34 and the rib 12 is not sealing contact since the ring 10 includesone or more slots 40 in its outer periphery, thus putting the tank offluid 1 into communication with the groove 13 of the piston. In thisexample, sealing between the piston 2 and the ring 10 is provided bycontact between the rib 14 and the groove 15. This sealing is reinforcedby the radial damping due to the sealing lip 34 which presses the rib 12between the rib 14. Thus, the rib 14 is also wedged in the groove 15 andparticipates in wedging the piston 2 on the ring 10.

Although they are advantageous for reasons explained below, the slots 40may be omitted.

Optionally, as shown in FIG. 3B, the wedging and the sealing between thepiston 2 and the ring 10 may be provided by contact between the sealinglip 34 and the ring 10, providing said ring 10 no longer includes anyslots 40. It is then no longer necessary to provide a rib or a groove onthe piston 2 or on the ring 10.

When the user holds the device between the thumb and two fingers, andpresses simultaneously on the thrust wings 23 of the pump body 22 and onthe thrust surface 20 of the pusher 3, the piston 2 tends to move downtogether with the pusher 3 towards the end wall 16 of the cylindricaltank 1. The fluid contained in the cylindrical tank 1 is generallyincompressible, such that the pressure of said fluid increases withoutsignificant displacement of the pusher 3 relative to the pump body 22.This pressure exerts a force on the piston 2 tending to move it awayfrom the end wall 16 of the cylindrical tank 1. When the ring 10includes the slots 40 of FIG. 3, the pressure of the fluid acts on agreater area of the piston and thus the force applied to the. piston bysaid pressure is correspondingly increased, thereby facilitating releaseof the piston 2. Once said force is sufficient to disconnect the piston2 from the ring 10, the piston 2 is pushed back upwards while the pusher3 together with the rod 4 and the ring 10 begins to move downwardstowards the end wall 16 of the cylindrical tank 1. In this way, theinternal sleeve 11 of the piston 2 is pushed into abutment against theannular wall 9 of the pusher 3, and a space 35 is established betweenthe piston 2 and the ring 10, as shown in FIG. 4. When the sleeve 11 isbrought into abutment against the annular wall 9 under the effect of thepressure that obtains inside the fluid tank 1 and of the frictionbetween the piston 2 and said tank 1, then contact between the sleeve 11and the annular wall 9 is sealing contact. Advantageously the annularwall 9 includes an annular lip surface 42, that is clearly visible inFIG. 4A, that surrounds the cylindrical wall 7, and that forms an acuteangle with said cylindrical wall 7. The free end 43 of the sleeve 11comes into abutment against said surface 42 so that by the wedgingeffect, the surface 42 deforms the free end 43 of the sleeve 11 radiallyinwards, and presses it against the cylindrical wall 7 of the pusher. Inaddition, this deformation is accompanied by considerable pressure beingapplied by the surface 42 to the sleeve 11. Thus, the free end 43 of thesleeve 11 is in sealing contact with both the annular surface 42 and thecylindrical wall 7.

The space 35 puts the cylindrical tank 1 into communication with thegrooves 5 on the rod 4, such that the fluid contained in saidcylindrical tank 1 can be expelled via the passage 35, the grooves 5,and the outlet orifice 6, while the piston 2 and the ring 10 move downinside said cylindrical tank 1 towards the end wall 16. This motioncomes to an end when the ring 10 comes into abutment against said endwall 16. Advantageously, the ring 10 includes a face 17 facing towardsthe end wall 16 and which is substantially complementary in shape to theshape of said end wall 16 and of the bead 27, such that when the ring 10is in abutment against the end wall 16, substantially all of the fluidcontained in the cylindrical tank 1 has been expelled. This serves tolimit the loss of a fraction of the fluid contained in the cylindricaltank, which is particularly useful when the fluid is expensive, or whenits use is subject to regulations (e.g. medicines based on prohibiteddrugs).

FIG. 5 shows a variant of the FIG. 1 device in which resilient meanssuch as a helical spring 36 are disposed between the annular wall of thepusher 3 and the piston 2 so as to urge the piston 2 resiliently towardsthe ring 10. This variant may be used advantageously, in particular whenthe volume of the dose to be sprayed is relatively large, and where thestroke of the piston 2 in the cylindrical tank 1 is relatively large.Under such circumstances, it could happen that a user might interrupt orslow down the motion of the piston 2 inside the cylindrical tank 1during the stroke of said piston 2. Under such circumstances, thepressure inside the cylindrical tank 1 would fall off and the helicalspring 36 would urge the piston 2 towards the ting 10 isolating thecylindrical tank 1 again from the outlet grooves 5. The piston 2 wouldthen move away from the ting 10 only once the pressure inside thecylindrical tank 2 has again become sufficient to overcome the force ofthe spring 36. This serves to guarantee that the fluid leaves the devicein the form of a fine spray. Furthermore, the helical spring 36reinforces the wedging of the piston 2 against the ring 10 when saidpiston is in its storage position.

FIGS. 6 and 7 show another variant of the device of the invention inwhich the internal sleeve 11 of the piston 2 is placed in abutmentagainst the annular wall 9 when the piston is in its storage position.Thus, displacement of the piston towards its actuation position, asshown in FIG. 7, is achieved by deforming a portion of the internalsleeve 11 of the piston radially inwards in the vicinity of the annularwall 9 of the pusher.

In this variant of FIGS. 6 and 7, it is particularly advantageous forthe ring 10 to include a cylindrical surface 44 over which acomplementary cylindrical portion of the piston slides in sealingcontact. If the height of the cylindrical surface 44 is written h, thepiston 2 must move away from the ring 10 by the distance h beforereleasing a passage between the fluid tank 1 and the outlet grooves 5.This distance h travelled by the piston corresponds to a predeterminedcompression of the sleeve 11 which itself corresponds to a predeterminedforce exerted by the sleeve 11 on the piston 2: thus, it is ensures thatthe fluid is expelled only providing the pressure inside the tank 1 hasreached a predetermined value, thereby ensuring that the fluid issprayed finely.

FIG. 9 shows a variant of the device of FIGS. 6 and 7 in which theinternal sleeve 11 of the piston includes longitudinal slits 37 whichextend over a fraction of its length in the vicinity of the annular wall9 of the pusher 3, thereby facilitating deformation of said internalsleeve 11.

In the variant of FIG. 9, sealing between the piston 2 and the pushercan no longer be provided at the annular wall 9. It is thereforepossible to provide a peripheral sealing lip 45 between the sleeve 11 ofthe piston and the cylindrical wall 7 of the pusher, as shown in FIG.10. This lip 45 may be formed on the inside of the sleeve 11, forexample, but it could also be formed outside the cylindrical wall 7. Itwill be observed that the above-described variants of the device of theinvention could also be fined with the sealing lip 45 as a replacementfor the sealing by abutment between the sleeve 11 and the wall 9.

The device of the invention may be filled with fluid by performing thefollowing method:

the device is placed in a vacuum chamber, with the orifice 26 of thetank 1 pointing upwards;

the vacuum chamber is evacuated;

a volume of fluid as measured by external measurement means is insertedinto the cylindrical tank 1, said volume being less than the totalvolume of said cylindrical tank 1; and

the orifice 26 is plugged under a vacuum.

The step of evacuating the chamber may take place after the step ofinserting an externally measured volume of fluid in the tank 1.

Thus, the volume of fluid inserted into the tank 1 is selected to lie inthe range 0 to a maximum volume. This is particularly advantageousinsofar as the same spray device of the invention can be used to containvarious doses of fluid, thus enabling it to be manufactured in largequantities and thus at reduced cost. After the orifice 26 has beenplugged and after the device has been removed from the vacuum chamber,if the volume of fluid is less than the total volume of the tank 1, thenthe piston 2 slides into the tank 1 under drive from externalatmospheric pressure until the inside volume of the tank 1 becomessubstantially equal to the volume of fluid that it contains.

As shown in FIG. 11, the enlarged base 19 of the endpiece 18 may includeslits 46 enabling the position of the tank 1 relative to the piston 2 tobe adjusted accurately so as to fix the maximum volume of fluid that canbe contained in said tank 1 accurately.

In addition, the slits 46 make it possible to press against the piston 2and not against the piston 3 while said piston is being installed insidethe cylindrical tank 1. This prevents the piston 2 from leaving itsstorage position during installation, because of the friction betweensaid piston and the cylindrical tank 1.

Advantageously, the orifice 26 in the end wall 16 may be extendedoutwards by a duct 47 provided with longitudinal slits 48. Thus, thebead 27 can be partially inserted into the duct 47 without closing theorifice 26 which is then in communication with the outside via the slits48. The manufacturer who fills the tank 1 is generally not themanufacturer of the device itself, and under such circumstances thefilling manufacturer needs merely to push the bead 27 in as far as theorifice 26 in order to plug said orifice after the tank 1 has beenfilled.

FIGS. 12 to 14 show a variant of the invention that seeks to provide amore reliable guarantee that the device remains in its storage position.For greater clarity, the piston 2 is not shown, nor is the rod 4 or thering 10. For this purpose, the tank 1 includes two grooves 100 in aplane perpendicular to the axis of the device, and each groove 100communicates at one of its ends with an axial groove 101 going away fromthe pusher 3. In addition, the pusher 3 includes two substantially axialresilient arms 102 each of which extends as far as a free end that isprovided with a catch 103 that, in the rest position, penetrates into agroove 100 at its end that does not communicate with an axial groove101. In the rest position, the pusher 3 is thus held in place axiallyrelative to the tank 1. To actuate the device, the pusher 3 is rotatedrelative to the tank 1 through about one-fourth of a turn, until thecatches 103 face the axial grooves 101.

During such rotation, the resilient arms 102 are pushed radially inwardsby ramps 110 formed in the bottoms of the grooves 100, and at the end ofrotation the catches snap into the axial grooves 101 such that thepusher can no longer be returned to its storage position. This makes iteasy to see whether a device has already been used.

In FIG. 15, a spot weld 104 is made between the pusher 3 and the tank 1in order to guarantee that these two parts do not move relative to eachother during storage or transport, and to show up any opening of thedevice or actuation of the device since the spot weld 104 is brokenduring opening or actuation.

In FIG. 16, the device includes an anti-opening safety mechanismconstituted by resilient catches 105 snapped into orifices 106 of thepusher while the device is in its storage position. The catches have abottom face 105a with the normal thereto extending axially away from theoutlet 30 of the pusher 3, and a top sloping face 105b whose normal hasan axial component directed towards the endpiece 18 and a radialcomponent directed towards the outside. The bottom face 105a comes intoabutment against the wall of the pusher, preventing the tank 1 frombeing withdrawn, whereas when the tank 1 is urged towards the outlet 30of the pusher, the sloping face 105b pushes the corresponding catch 105radially inwards, thereby disengaging the orifice 106 thus enablingactuation to take place. Advantageously, the pusher 3 further includesorifices 107 in which the catches 105 are engaged when the device is inits end-of-actuation position, so that the tank 1 cannot be opened forthe purpose of being refilled. Under such circumstances, it isadvantageous for the tank 1 to be guided in its axial motion relative tothe pusher 3 in such a manner that the catches 105 are certain topenetrate into the orifices 107.

In FIG. 17, the pusher 3 includes removable pellets 108 and the tank 1includes corresponding axial rods 109 that punch out the pellets 108,detaching them from the pusher 3 during actuation. This preventsuntimely actuation during storage or transport, and detached pellets 108demonstrate the device has already been actuated.

It may be observed that the variants of FIGS. 12 to 17 could be appliedto a device in which the piston is not held in place by wedging, andmore generally to any device of the same general type as that of theinvention having a cylindrical tank, and a piston which is secured to apusher and which is provided with an outlet passage.

What is claimed is:
 1. A device for spraying a single dose of a fluid individed form, the device comprising at least:a cylindrical tank (1)containing said single dose of fluid; a piston (2) slidable in a sealedmanner in said cylindrical tank (1); a pusher for actuating the piston(2); and an outlet passage (5, 6) capable of communicating with saidcylindrical tank (1) wherein said piston (2) is slidably mounted on saidpusher and is displaceable relative to said pusher between a storageposition in which it seals said cylindrical tank and preventscommunication between said outlet passage (5, 6) and said cylindricaltank (1), and an actuation position in which it puts said outlet passage(5, 6) into communication with the cylindrical tank (1), the pistonbeing placed so that a pressure obtaining in the cylindrical tank (1)attracts the piston (2) towards its actuation position, and wherein thepiston (2) is held in its storage position by wedging, on the pusher,and can be displaced towards its actuation position only if the pressurethat obtains inside the cylindrical tank is sufficient for unwedging it,said pressure being obtained by pushing on the pusher.
 2. A deviceaccording to claim 1, further characterized in that the pusher (3, 4)comprises cylindrical portion (7) that extends between an end (8) closeto the cylindrical tank (1) and an abutment (9) that is further from thecylindrical tank (1), said end (8) close to the fluid tank is secured toa ring (10), said fluid outlet passage (5, 6) is disposed at least inpart inside said cylindrical portion (7) of the pusher, said fluidoutlet passage opens out from said cylindrical portion (7) between saidring (10) and said abutment (9) in the vicinity of said ring (10), thepiston includes an internal sleeve (11) that slided over saidcylindrical portion (7) of the pusher and said piston (2) is in sealingcontact with said ring (10) while in the storage position.
 3. A deviceaccording to claim 2, further characterized in that the piston (2)includes an outside peripheral sealing lip (34) which slides in sealedmanner inside the cylindrical tank (1) and which is wedged between saidtank (1) and the ring (10) when the piston (2) is in its storageposition.
 4. A device according to claim 3, further characterized inthat the ring (10) includes an annular rib (12) extending towards thepiston (2), the piston includes an annular groove (13) adapted toreceive the rib (12) of the ring, the piston (2) includes an annular rib(14) directed towards the ring (10) and inside said annular groove (13),and the ring (10) includes an annular groove (15) adapted to receive theannular rib (14) of the piston (2).
 5. A device according to claim 4,further characterized in that the (10) includes at least one passage(40) putting the tank (1) into communication with the groove (13) of thepiston (2) when said piston (2) is in its storage position, and in thatthe rib (14) of the piston is in sealing contact with the groove (15) ofthe ring (10).
 6. A device according to claim 2, further characterizedin that the cylindrical tank (1) includes an end wall (16), and the ring(10) includes a face (17) facing towards said end wall (16) andsubstantially complementary in shape to said end wall (16), and in thatsaid face (17) of the ring (10) comes into abutment against said endwall (16) at the end of the stroke of the piston (2), such thatsubstantially all of the fluid contained in the tank (1) is expelled. 7.A device according to claim 2, further characterized in that the piston(2) is urged towards its storage position by resilient means (36, 11).8. A device according to claim 2, further characterized in that internalsleeve (11) of the piston (2) presses against the abutment (9) of thepusher when the piston (2) is in its storage position, and thedisplacement of the piston (2) towards its actuation position takesplace by deformation of at least a portion of the internal sleeve (11).9. A device according to claim 8, further characterized in that theinternal sleeve (11) of the piston (2) includes longitudinal slits (37)over a fraction of its length in the vicinity of said abutment (9) ofthe pusher so as to facilitate deformation of said internal sleeve (11).10. A device according to claim 2, further characterized in that thesleeve (11) is pressed in sealed contact against said abutment (9) whenthe piston is in its actuation position.
 11. A device according to claim10, further characterized in that said abutment (9) includes a concaveannular surface (42) surrounding the cylindrical wall (7) with itsconcave side facing towards the sleeve (11), and in that said concaveannular surface (42) deforms a free end (43) of said sleeve (11)radially towards the inside when the piston (2) is its actuationposition.
 12. A device according to claim 2, further characterized inthat the sleeve (11) of the piston (2) slides in sealed manner over thecylindrical wall (7) of the pusher.
 13. A device according to claim 2,further characterized in that the piston (2) includes a cylindricalportion (14) which slides over a complementary cylindrical portion (15)of the ring (10) while continuing to interrupt communication between thecylindrical tank (1) and the fluid outlet passage (5, 6) so long as thepiston (2) has not moved away from the ring (10) by a predetermineddistance (h).
 14. A device according to claim 2, further characterizedin that at rest said piston (2) is in sealing contact with said ring(10) around a peripheral line close to the cylindrical wall of the tank(1) so that only a radially outer portion of the piston is initiallyexposed to the pressure that obtains inside the tank (1), such that thesection of the piston (2) which is exposed to the pressure that obtainsinside the tank increases suddenly when the piston (2) separates fromthe ring (10), thereby encouraging clean opening of communicationbetween the tank (1) and the outlet passage (5, 6).
 15. A deviceaccording to claim 1, further characterized in that the cylindricalfluid tank (1) includes a filler orifice (26) suitable for receiving aplugging bead (27), and said orifice (26) is extended towards theoutside of the tank (1) by a duct (47) provided with longitudinal slits(48), said bead (27) being capable of being received as a force-fitinside said duct (47) in an intermediate position where it allows thetank (1) to communicate with the outside via said longitudinal slits(48).
 16. A device according to claim 1, further characterized in thatit includes resilient means (36, 11) urging the piston (2) towards arespective closure position.
 17. A device according to claim 1 furthercharacterized in that it includes locking means that prevent the pusher(3) from moving axially relative to the tank (1).
 18. A device accordingto claim 17, further characterized in that said locking means (100, 103)are unlockable by rotating the pusher (3) relative to the tank (1). 19.A device according to claim 18, further characterized in that thelocking means (100, 103) remain blocked in the unlocked position afterthey have been unlocked.
 20. A device according to claim 17, furthercharacterized in that said locking means are constituted by at least onebreakable bridge of material (104) between the pusher (3) and the tank(1).
 21. A device according to claim 1, further characterized in that itincludes means for preventing involuntary actuation thereof.
 22. Adevice according to claim 21, further characterized in that it includesat least one zone of breakable material (108) that forms an abutmentopposing actuation and that is broken during actuation.
 23. A deviceaccording to claim 1, further characterized in that it includes meansfor preventing the tank (1) from being separated from the pusher (3).24. A device according to claim 23, further characterized in that saidmeans include snap-fastening means (105) that are in the snap-fastenedposition at least while the device is in its rest position.
 25. A deviceaccording to claim 24, further characterized in that said snap-fasteningmeans are also in the snap-fastened position when the device in itsend-of-actuation position.